Apparatus for feeding coal



EJuly 22, 1952 L. E. sHAw APPARATUS FOR FEEDING COAL Filed May 25, 1948 INVENTOR. -LOUI5 EHTON 5HH\/\- ATTORN EY.

Patented July 22, 1952 UNITED STATES TENT oFFlcE APPARATUS FOR FEEDING COAL Louis Eaton Shaw, East Grange, N. J.

Application May 25, 1948, Serial No. .28,998

12 Claims. (Cl. 21d-i7) This invention relates to the art of feeding coal or other semi-huid material when stored in a bin to the intake of withdrawal mechanism, such as a Stoker, located low in the pile of material in the bin.

In most household heating equipment coal is stored to the extent of Several tons in a bin which is usually a small rectangular room in the basement of the home and withdrawn as needed by means of a Stoker whose inlet is located adjacent the bottom and center of the coal pile in the bin. As the coal is withdrawn it tends to create a depression forming a vacant space in the top of the coal pile directly above the inlet and which space tends to assume the form-of an inverted cone with its apex pointing downwardly towards the inlet. With coal the angle of repose is about iorty-ve degrees so that the space assumes a right circular cone whose side forms an angle of forty-live degrees ywith both the horizontal and vertical. When an amount of coal has been withdrawn to cause the apex to reach the intake no more coal is fed to the'stoker despite the fact that there is a material amount of coal still in the bin and surrounding the conical vacant space.

It has been suggested that the householder climb into the bin from time to time and manually shovel the inactive coal into the depression and thus maintain the necessary hydrostatic flow head through the pile to the stoker intake, and in this way utilize the otherwise unused and stagnant coal. This may involve the lifting of a ton or more of coal, with the expenditure of a material amount of labor and anyhow is a laborious and dirty chore which is usually put off until the Stoker fails by reason of the failure of the supply thereto.

The primary object of the invention is to avoid this manual labor and instead to provide an improved technique for maintaining constant a flow of material through the pile thereof to the Stoker inlet and to maintain the flow until the supply in the bin has been substantially exhausted.

Broadly, this objective is attained by slowly and gently, but continuously, sweeping the coal at the top oi the pile circularly with a shallow scooping gathering or leveling action to cause a relatively small volume of the coal in advance of the scoop to movein a long, narrow, wavelike stream from the outer edge ofthe pile inwardly towards the center thereof and thus constantly fill up any depression in the top of the pile or even prevent its formation.

With reference to the apparatus aspect of the disclosure an object ofthe invention'is to provide a simplified and inexpensive form of household equipment for practicing the method aspect of the disclosure and thus to provide apparatus which will automatically tend to maintain a iiow of the material to the Stoker intake until the bottom of the pile is reached and to do this without necessity of moving any material amount of the coal in the pile.

Various other objects and advantages of the invention will be in part obvious from a consideration of the method features of the disclosure and from an inspection of the accompanying drawings oi one form of apparatus for practicing the method and in part will be more fully set forth in the following particular description of one method of practicing the invention vand one form oi apparatus, and the invention also consists in certain new and novel modications of the preferred method and of the preferred apparatus, l

and other features of construction and combination of parts hereinafter set forth and claimed.

in theV accompanying drawing:

Fig. l is a view in vertical section through a conventional form of coal bin with its mid-portion broken away to save space, equipped with a preferred embodiment of the apparatus aspect 0I" the invention and illustrating Vone stepy in the method aspect ci the disclosure;

Fig. 2 is an enlarged detail view of the upper portion of the coal gathering or leveling mechanism shown at the top of Fig. 1;

Fig. 3 is a detail view taken on the plane indicated by tde lined- 3 oi l, looking downwardly as indicated bythe arrows and particulariled and before the mechanism herein featured becomes operative.

In the drawings and referring to Fig. l, there is disclosed a coal bin A mounted on a oorB and extending between the floor and a ceiling structure C. The bin is of somewhat conventional iorm and includes tour outlining side walls D, E, F and` G. The wall F (see Fig. 6) contains a, coal supply window H through which the coal may be deliverd into the bin. There is disclosed a pile of coal I with an upper level J which assumes different forms as hereinafter disclosed. Coal is withdrawn conventionally from adjacent the bottom of the pile by means of a coal withdrawal mechanism K and is passed therethrough to the furnace stoker or other receiving device (not shown). The mechanism K includes a tubular bin feed L which contains a bin feed screw M. This screw projects beyond the bin feed and constitutes the intake to the stoker or withdrawal mechanism K. Mechanism K includes a stoker feed N of tubular form supplied from the bin feed and includes a stoker feed screw O for passing the coal therethrough and on to the stoker. The mechanism K is operated by a motor or other source of power indicated symbolically by the main drive shaft P and which drive shaft is geared to the bin feed screw M by a chain drive Q and is geared to the stoker feed screw N by a chain drive R. It is understood that the structure thus described is intended to represent any conventional form of coal bin which constitutes a source of supply for supplying coal to a furnace by means of a stoker mechanism.

` In such a situation there is installed a coalfeeding, coal-gathering and coal-pile-leveling mechanism particularly forming the apparatus aspect of this disclosure. The mechanism I includes a rugged head plate II bolted to the ceiling structure C. Secured to the head plate and depending therefrom is an overhead bearing I2 which supports the upper end of an upright I3 depending therefrom and mounted to rotate about a vertical axis a--b. The upper portion of the upright is formed of a short, solid shaft I4 whose upper end is outwardly flared to form a head flange I5. An antifriction bearing I5 is interposed between the flange I5 and the fixed bearing I 2. Located just below the antifriction bearing device is a graphite bronze thrust washer I1, and therebelow is a friction disk clutch which includes a large diametered, upper bevel gear element I8 loose on the solid shaft I4 and a lower element I9 slidable on shaft I4 and secured thereto by a key to rotate therewith. Secured to the shaft I4 below the friction clutch is a bearing collar 2I and a heavy spring 22 reacts between the collar 2| and the shiftable friction clutch element I9 to maintain the clutch in its normal operative frictional driving engagement with the element I8. The upright is braced and steadied in its upright position by means of an angle bracket 23, one end of which forms a flat plate 24 secured to the plate II by bolts 25. The lower end of the bracket 23 forms a collar 25 through which the shaft I4 extends. `Just below the bracket 23 a pipe T 21 is secured to the lower end of the shaft I4, and a pipe 28 screwed into the pipe T depends towards the bottom of the bin and acts as a guide for the sweep hereinafter described. A pipe fiange 29 is secured to the lower end of the pipe 28 to limit the fall of the sweep. A long pipe 30, hereinafter referred to as a drag arm, is screwed into the side bell of the pipe T 21 and extends horizontally outwardly away from the upright I3. A sweep 3I is located below the drag arm and in the form illustrated in Fig. 3 is in the form of an involute curve, the inner end of which is bent circularly back upon itself to form a loose cylindrical form of bearing 32 slidably mounted for free vertical movement on the pipe 28. The sweep includes a long scraping blade 33 and is formed of a strip of fiat steel bent to form as best shown in Fig. 3. The scraping blade is provided at its outer free end 34 with a weighted block 35. In some cases the weight of the blade itself is sufcient to gain the desired scraping action. A drag chain 3B connects the outer ends of the drag arm 3U and sweep 3I to draw the sweep about the top of the coal in the bin as the drag arm rotates counterclockwise about the vertical axis of the upright in the direction indicated by the curved arrow in Fig. 3.1 l f As noted in Fig. 3 the angle formed'between the drag arm and the sweep is about one hundred and twenty degrees when the bin is full and the sweep is high up near the level of the arm, but this angle gradually decreases with the fall of the` level J until the angle is about ten degrees at the time when the outer end of the sweep is resting on the floor B of the bin.

The blade 33 is concaved on its advance side and for the most part is offset from a plane c-d (see Fig. 3) which passes through the axis of the upright and a point adjacent the free end 34.

The upright is rotated through a reducing gear device from the power shaft P. For this purpose a pinion 31, pinned to a secondary drive shaft 38 forms a bevel gear drive with the bevel gear element I8. The shaft 38 is mounted in spacedapart brackets 39 and 40 secured to the ceiling structure C and is geared to shaft P by means of a chain drive 4I so that the gathering apparatus and delivering mechanism are driven in unison. In one form of the invention and with rather small size coal the intergeared relation was set so that the upright I3 and associated parts revolve once in one hundred and fifty seconds while the bin screw M revolves once in thirty seconds, or at a ratio of five to one.

The drag Varm 3U is provided with a couple of hooks 42 for supporting the sweep in an elevatedf inoperative position as shown in Fig. 6.

In place of the form of sweep shown in the preceding gures, it is suggested that it be formed as shown at 43 in Fig. 4 of strips of flat metal riveted together. In this case a cylindrical bearv ing 44 for sliding loosely on the pipe 28 is con` nected to a straight tangential ar 45 by means of an inverted U-connection 46. While the bar 45 is shown extending vertically it is suggested that where the scraping blade is made thin and disposed to move horizontally it can more readily knife itself edgewise through the coal pile than where it faces the coal flatwise. Both of these forms function identically as does the preferred form of Fig. 3.

In order to show what would happen in a coal bin under normal conditions, that is, in the absence of the mechanism herein featured, reference is made to Fig. 5. In this case the feed mechanism has been operating on the coal pile until no more coal can be supplied to the screw M and the screw operates idly. In this case a' is surrounded by a mass of coal with inwardlyinclined top suface J depending from the side walls towards the axis a-b. Under these conditions there is a material amount of coal left in the bin and not available to the feed screw M. It is to avoid this condition that the instant invention is intended to function.

In operation it will be advisable before the bin is lled with a fresh supply of coal to lift the sweep bodily and hang it in an out-of-the-way position onto the hooks 42 and thus avoid burying the sweep beneath the coal pile as it is formed. Assuming that a quantity of coal has been delivered as by chute through the vwindow H it collects in the bin and in doing so is apt to assume the inclined level indicated at J in 6, high on the side nearest thewindow and sloping off sharply towards the opposite side. It may even so happen that the sweep is more or less covered by the coal as suggested in Fig. 6, but this is immaterial provided the sweep is not so far embedded as to create such resistance to moving as would cause the friction clutch to release itself. In this case, of course, the sweep would remain inoperative until the level of the coal became suiciently lowered to release the sweep and permit the clutch to reestablish operative connections.

As is usual with household heating devices, the stoker operation is under control of a motorcontrolling thermostat and when calling for heat the motor will drive the main shaft P. In the instant case this results in shaft P rotating slowly to drive the screws of the mechanism K and at the same time to drive the gathering or leveling apparatus I 0. As the sweep begins to revolve from the position suggested in Fig. 6, it

follows the irregularities of the surface J scrapes the coal from the high point or points to ll the low points, and in a short time has leveled it. From then on the sweep keeps the surface level or slightly convex and descends with it until its inner end forming the loose bearing 32 rests on the flange 29. During this time the blade 33 as it revolves scrapes up a limited quantity of coal from the high points of the pile and with a shallow, scraping or scooping action causes loose coal to flow as a stream inwardly towards the upright i3 and thus lls up any low points in the top level J. It is a feature of this disclosure that the sweep handles' only this small volume of coal at the top of the pile leaving the balance of the coal to fall gravitationally assisted;

of course by the withdrawal action of the bin feed screw. The top of the pile during most of the operation assumes a slightly domed form high atthe axis a-b and sloping off in all directions therefrom towards the perimeter of the circle defined by the outer end 34 of the sweep, as shown in Fig. 1. This sweeping action continues until the outer end of the sweep rests on and scrapes idly on the fioor of the bin. When the coal level drops below the level of the top of the bin :feed tube L, the sweep rides up over the tube en one side, slides off on the other side, and continues its operation until practically all of the coal within the circle of the sweep has been fed to the intake end of the screw M.

In the case of a square or rectangular form of bin some coal will remain in the four corners, as indicated at T in Fig. 1, but the amount so remaining unused in the bin is not of any serious amount. Usually the householder does not permit the bin to become empty, but even so the small volume T remaining in the corners can be raked down within the sweep circle and used if desired.

At any time it is desired to reiill the bin the sweep is elevated off the top of the pipe or bin floor as the case may be and hung onto the hooks 32, as shown in Fig. 6, until the fresh supply of coal has been added, after which the sweep is unhooked and permitted to fall onto the top of the coal pile and the operation continues as thus described.

The apparatus thus disclosed is independent of the bin feed worm, so that either'the apparatus I0 or the mechanism K can be separately repaired one without affecting the other. There are no gears or bearings beneath the coal; there are no lubricating problems; vno excessive wear possible by reason of coal dust getting into inaccessible mechanism.l The apparatus is easily installed and can be operated at relatively low cost.

It is appreciated Viewing Fig. 5 that there is no coal above the intake of the withdrawal mechanism and thus there is no hydrostatic head of material iiowing into the mechanism despite the fact that there is a material amount of coal remaining in the bin. With the leveling device herein featured operating there is a hydrostatic head operating along the vertical axis a-b and thus a down flow of coal in the pile so long as there is any material within the circle defined by the sweep. For instance, viewing the situation as shown in Fig. 1 there is a head and resulting stream of coal flowing under pressure in the area between the flange 29 and screw M, despite the fact that the outer edge of the top J is actually below'the level ofthe flange 29.

The tendency of the swep to dome the top of the pile keeps the material available to the screw M until the supply is exhausted.

l. claim:

l. A coal storing and feeding device including a bin for storing a pile of coal, feeding mechanism for withdrawing coal from the pile in the bin, said mechanism including a feed screw whose intake end is adjacent the bottom of the bin, sweep mechanism including an upright whose lower end is adjacent the intake end of the feed scre.' said mechanism including a sweep having one end guided for free falling movement vertically on said upright and adapted to be lifted manually along the upright into an inoperative position above the coal pile, said sweep when in operative positiony resting on top of the pile of coal in the bin in a substantially horizontal position and free to take whatever position may be imposed thereon by its instant point of contact with the top of the pile and in scraping engagement with the top of the coal, mechanism for dragging the sweep circularly across the coal pile and about the upright as a center, a single power means for operating the last named mechanism and the feed screw in synchronism, said power means including a reducing device for revolving the sweep at a materially less rate than the feed screw revolves.

2. The device defined in claim 1 and in'which the sweep mechanism includes a normally operative spring-loaded friction clutch located between the sweep and. the power means to break the connection therebetween in the levent the sweep meets a resistance to its rotative movement which it cannot overcome while the power means connected through the sweep acts on the coal pile in a tendency to remove the resistance to the rotative movement of the sweep.

3. In a device of the class described, the combination with a bin for storing a pile of coal or like semi-fiowable material and which bin is provided with an outlet for the material located adjacent the center of the bottom of the bin and through which outlet the material flows in a tendency normally to create a conical space end mounted to turn about a vertical axis located approximately at the vertical of the space, said sweep including a blade free to rock vertically relative-to said axis and disposed to have its lower edge rest at all times gravitationally on top of and in scraping engagement with the top of the pile of material and free to fall with the top of the pile as said top lowers itself by reason of the withdrawal of material from the pile, and power-actuated mechanism operatively connected to the sweep in all the vertically variable positions thereof to revolve it about its axis.

4. A device for shifting coal or like semi-flowable material at the top of a pile of the same circularly towards the center of a sweep circle and thus tend to maintain the top of the pile level, said device including an upright mounted for rotary movement about a vertical axis and disposed with its lower portion within the pile and adjacent its bottom, a drag arm located above the pile and having one end thereof secured to the upright to rotate therewith, a sweep normally resting gravitationally on top of the pile, having one end journaled on the upright below the arm for rotary movement about the upright and guided on the upright for free vertical falling movement, a flexible draft element connecting the other ends of the arm and sweep for causing the sweep to scrape the material along the top of the pile and to feed the material so scraped towards the upright and power means operatively connected to the upright to rotate the same.

5. In a device of the class described, the combination of an overhead bearing, an upright journaled at its upper end for free rotary movement in the bearing and depending therefrom, a power drive operatively connected for rotating the upright, a drag arm secured to the upright to turn therewith and extending horizontally therefrom, a sweep provided at its inner end with a bearing loosely encircling the upright below the drag arm and free to move vertically on the upright, and a flexible drag connection between the arm and sweep.

6. The device defined in claim and in which the sweep includes an upstanding strip of metal forming a scraping edge and whose outer end is weighted in a tendency to drag the outer end into the pile.

7. In a device for feeding semi-iiowable material in a pile horizontally across the top of the pile as the top lowers itself incidental to withdrawing material from the pile, the combination with an upright, fixed against axial movement, a long, upstanding, blade forming a sweep having its inner end articulately connected to and loosely guided on the upright for rotary movement and free to fall gravitationally along the upright and thus to maintain itself automatically in operative engagement with the top of the pile as the top becomes lowered, and power means operatively connected to the sweep to cause it to rotate about the axially iixed upright as a center in all the vertically adjustable positions of the sweep.

8. The device dened in claim '7 and in which the sweep includes a scraping blade disposed for the most part offset from a vertical plane containing the axis of rotation of the sweep at the upright and a point adjacent the outer end of the sweep and forms a concave sweeping surface on its advancing side.

9. In a device of the class described, the combination of an upright, a drag arm mounted for rotation about the axis of the upright and otherwise xed in space, power means for revolving the drag arm about said axis, a sweep having one end loosely guided on the upright for rotary movement about said axis and free to fall gravitationally while guided on said upright and a connection between the arm and sweep for causing the arm to rotate the sweep in all vertical operative positions of the sweep.

10. In a device of the class described, the coinbination of a vertically extending guide provided at its lower end with a stop fixed in space, a sweep having its inner end bent back upon itself to form a bearing loose on the guide and free to fall with the sweep until it rests on the stop, the outer end of the sweep provided with a weight and the portion of the sweep between the weight and bearing forming an upstanding scraping blade, and power means for rotating the sweep about the guide as an axis in all positions of the sweep.

11. In a device of the class described, the combination of a coal bin, power driven mechanism for withdrawing coal from adjacent the center of the bottom of the bin, an upright in the bin disposed with its lower end adjacent the intake of the withdrawing mechanism, means for feeding coal from the top of the coal in the bin inwardly towards the upright and thus above the intake of the withdrawing mechanism and into position to permit the coal to fall gravitationally towards said withdrawing mechanism, said means including a scraping blade extending radially from the upright, atv all times disposed in position resting on the coal and operating on the coal forming the instant top level of the coal in the bin to move any coal collected thereby inwardly towards the upright, said blade having rotary movement approximately in horizontal planes as the lowering of the coal level permits a lowering of the blade, said blade having its inner end loosely connected to the upright and guided thereon for free vertical movement, the outer end of the blade having a limited freedom of vertical movement about the upright as an axis of turn, and power means at the upright for revolving the blade about the upright.

12. In a device for leveling the top of a pile of loose, semi-ilowable material, the combination of a long scraping blade extending normally in a substantially horizontal direction and disposed to have its lower edge normally engage the top of the pile, said blade supported entirely by the material and free to take whatever inclination to the horizontal which may be imposed thereon by the inclination of the top of the pile, vertically extending means for guiding one end of the blade and otherwise independent of the blade, and power means for rotating the blade in all operative positions of the same to cause its advance side to bear against the material in advance of the same to sweep the material engaged thereby radially inward towards the axis of rotation of the blade, the weight of the blade alone regulating and controlling the depth at which its lower edge penetrates into the top of the pile.

' LOUIS EATON SHAW.

(References on following page) 9 REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 98,412 Pry Dec. 28, 1869 275,186 Gass Apr. 3, 1883 1,257,161 Walters Feb. 19, 1918 Number Number Name Date Kutz Dec. 1'7, 1929 Burton Apr. 25, 1933 Weinig Nov. 11, 1941 FOREIGN PATENTS Country Date Great Britain Aug. 15, 1918 

